Question: $210$ is what percent of $500$ ?
Answer: Having a percent of something means that you get that percent out of every $100$ We can set up a proportion to find out what percent of $500$ we need to take to get $210$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{\text{part}}}{{\text{whole}}}$ Which things do we know, and what are we trying to find? We are trying to find the ${\text{percent}}$ . Is $500$ the ${\text{part}}$ or the ${\text{whole}}$ The $500$ is the ${\text{whole}}$ . This means the ${\text{part}}$ is $210$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{210}}{{500}}$ If we divide the denominator of the fraction on the right by $5$ , it will be the same denominator of the fraction on the left. To keep things equal, let's also divide the numerator on the right by $5$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{210 \div 5}}{{500 \div 5}}$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{42}}{{100}}$ $ {\text{percent}} = {42}$ So $210$ is $42\%$ of $500$.